1. Field of the Invention
The present invention relates to a stereoscopic imaging apparatus, and more particularly, to a technique in which object images having passed through different regions in a predetermined direction of a photographing optical system are imaged onto image sensors to obtain a left viewpoint image and a right viewpoint image.
2. Description of the Related Art
Conventionally, a stereoscopic imaging apparatus having an optical system as shown in FIG. 15 is known in the art (see JP2009-527007A).
This optical system has a configuration in which object images having passed through different regions in the horizontal direction of a main lens 1 and a relay lens 2 are pupil-split by a mirror 4 and are imaged onto image sensors 7 and 8 through imaging lenses 5 and 6, respectively.
FIGS. 16A to 16C show separate states of an image imaged onto an image sensor depending on a difference between front-focus, in-focus (best focus), and back-focus. Note that, in order to compare the difference in the separate state with the focusing, the mirror 4 shown in FIG. 15 is omitted in FIGS. 16A to 16C.
Among the pupil-split images, images that are in focus as shown in FIG. 16B are imaged (match) at the same position on the image sensor, whereas images that are front and back focused shown in FIGS. 16A and 16C are imaged (separate) at different positions on the image sensor.
Therefore, by obtaining object images which are pupil-split in the horizontal direction using the image sensors 7 and 8, it is possible to obtain a left viewpoint image and a right viewpoint image (namely, 3D image) of which the parallaxes are different depending on an object distance.
Moreover, JP2009-168995A discloses an imaging apparatus which acquires a left viewpoint image and a right viewpoint image corresponding to object images which are pupil-split in the horizontal direction similarly to the above and performs focus detection (detection of a defocus amount) with respect to approximately the entire area of a photographic screen.